The present invention relates to a permeable screen for use in a projection type television receiver and a manufacturing method thereof.
An example of a conventional permeable screen is shown in FIGS. 9 and 10.
As shown in FIG. 9, the conventional permeable screen is two-sheets comprising a Fresnel lens sheet 61 having a Fresnel lens 64, and a lenticular lens sheet 62 overlaid on the front side of the Fresnel lens sheet 61.
In the lenticular lens sheet 62, in order to enhance matching of the picture and expand the vertical view field, light dispersing fine particles, such as glass and high molecular material which function as dispersing agent 68, are mixed in a screen substrate.
On both sides of the lenticular lens sheet 62, cylindrical lenticular lenses 65, 66 are formed.
Furthermore, to prevent reduction in contrast due to external light, protruding black stripes indicated by external light absorption layer 67 are formed in specific pitch stripes in the non-focusing area of the incident side of the lenticular lens 65.
However, as shown in FIG. 10, for the conventional construction, part of the incident light becomes stray light as indicated by incident ray 63a in FIG. 10. This occurs because the dispersing agent 68 is mixed in the lenticular lens sheet 62.
As a result, various problems such as deterioration of resolution, worsening of color performance due to color shift or color shading, and lowering of brightness due to loss of quantity of exit light may be caused.
Moreover, part of the dispersing agent projects on the surface of the cylindrical lenticular lens 65 of the lenticular lens sheet 62 or the protruding black stripes 67 in the non-focusing area, and therefore, the surface of the lenticular lens sheet 62 is undulated.
Accordingly, when the side surface of the lenticular lens sheet 62 where light exits is exposed to external light, irregular reflection occurs, and the screen surface becomes whitish. As a consequence, the contrast is lowered.
To improve the lowering in brightness and lowering in contrast due to external light, as shown in FIG. 10, a method is proposed of disposing a glass or plastic transparent panel 69 for lowering the light permeability on the front surface of the screen.
In this case, however, undesired external light images from fluorescent lamps, room light, surrounding people, windows and other objects are often reflected on the transparent panel 69, which makes it difficult to observe the screen.
A conventional permeable screen cabinet including the conventional permeable screen is shown in FIG. 11.
As shown in FIG. 11, to mount the conventional permeable screen on a television receiver cabinet main body 77, the transparent panel 69, lenticular lens sheet 62 and Fresnel lens sheet 61 must be affixed to a mounting boss 72 on which a mounting frame 71 is formed, by tightening with a mounting bracket 73 and setscrews 74.
As a result, mounting parts for mounting the screen are required, the number of parts are numerous and the mounting processes is long, thereby causing raised costs.